Nike’s Breaking2 project is more than just a slick marketing exercise for a new running shoe. The effort will tell us something important about how fast elite human athletic performance might be improved. But the project should also force us to ask some challenging questions about human enhancement and who it is for.

Nike’s formula for breaking the two hour marathon starts with three of the world’s fastest runners: Eliud Kipchoge of Kenya, Lelisa Desisa of Ethiopia and Zersenay Tadese of Eritrea. Kipchoge won Gold in the marathon in Rio last year, Desisa won the Boston Marathon in 2013 and 2015 and Tadese is the world record holder for the half marathon.

That system is a high tech new shoe, the Nike VaporFly Elite specially designed for the three runners in the project. The consumer version will be called Zoom VaporFly 4%. The 4% is in the name because the shoe is supposed to reduce the energy required to run by 4% by using a curved carbon-fiber plate embedded in the sole. That’s a big number, given that breaking two hours implies beating the current record by about 3%.

But as long as Nike is looking to technology to help elite runners run faster, why not just have the athletes strap on rollerblades and shatter the world record?

The IAAF explains that athletes may “compete barefoot or with footwear.” The purpose of shoes is to “give protection and stability to the feet and a firm grip on the ground.” Such shoes are not allowed “to provide any unfair additional assistance” beyond running barefoot.

A general consensus of the scientific community is that while shoes provide additional cushioning for the runner their additional mass requires more effort from the runner, “thus the two factors appeared to counteract each other.” In other words, running with shoes doesn’t provide any advantage over running barefoot.

But the new Nike shoe was specifically designed to provide an “additional assistance.” If the IAAF rules simply prohibited “additional assistance” then the shoe would clearly be illegal in IAAF competitions. But the rule says “unfair additional assistance” – So is the shoe “unfair”?

The IAAF rulebook doesn’t define unfair. But the rules do allow us to define what that means. This is where things get really interesting.

The Court further concluded that “at least some IAAF officials had determined that they did not want Mr Pistorius to be acknowledged as eligible to compete in international IAAF-sanctioned events, regardless of the results that properly conducted scientific studies might demonstrate.” They didn’t want an athlete running on prosthetics in the Olympics. One IAAF official explained that including Pistorius “affects the purity of sport.”

Thus, if we apply the same standards to Nike’s fancy new shoes that the IAAF applies to prosthetic limbs, then the shoes clearly are illegal under IAAF rules. They provide an overall competitive advantage over athletes not using the shoes. That is both what they were designed to do and also what is indicated by testing by my colleagues here at the University of Colorado. Not all athletes can use the shoes, because not all are sponsored by Nike. For the shoes to be allowed, proof would have to be provided that they do not provide an advantage.

So the IAAF finds itself in an interesting situation. If the new Nike shoes are to be allowed, then the same application of the rules would suggest that athletes running on blades should also be allowed to compete. Otherwise the message being sent is that human athletic performance can be enhanced using technology worn on the ends on one’s legs only if those legs have not been amputated.

Similarly, if athletes who run on blades are in fact to be excluded, then the same application of the rules would suggest that the new Nike shoes should also be banned. The issue here immediately becomes one of discrimination and treatment under the rules that depends on the length of one’s legs, not the technology that one affixes to their ends.

Athletes and their sponsors are always looking to eke out every bit of additional performance that they can. Technology offers one important route to performance enhancement, sometimes so much so that it must be regulated, as occurs with many performance enhancing drugs. The new Nike shoe is just the latest innovation in trying to achieve a bit more, and Nike hopes, to sell a lot more shoes.

The new shoe also provides us an opportunity to ask some difficult questions about who technology is for and what it means to use technology fairly in sport. Certainly, applying technology to breaking the threshold of a 2 hour marathon would be quite a notable achievement. So too would be applying technology to allow amputees to compete fairly in the Olympic games. But only one of these applications represents a more humane use of technology.